1. Field of the Invention
This invention relates to a photosensitive resin composition, more specifically to a photosensitive resin composition having an excellent film property, heat-resistance, adhesivity and image-formability which does not require complex steps for preparation and does not cause contamination with chlorides.
2. Prior Art
In the semiconductor industries, inorganic materials have conventionally been used for interlaminar insulation. Recently, organic materials having an excellent heat-resistance such as a polyimide resin have been put to use as materials for interlaminar insulation because of properties thereof.
A process for forming a pattern in a semiconductor integrated circuit or forming a pattern of a circuit of a print substrate comprises complex and various steps such as formation of a resist material film on the substrate surface; exposure of required portion to light; removal of unnecessary portion by etching or so; and washing of the base surface. Therefore, development of heat-resistant photosensitive materials have been desired, which enables the required portion of the resist material to be used as insulating materials even after the pattern is formed by exposure to light and development.
As such a material, heat-resistant photosensitive materials comprising, for example, a photosensitive polyimide or a cyclized polybutadiene as a base polymer have been proposed. The photosensitive polyimide has attracted attentions since it has an excellent heat-resistance and impurities can easily be removed.
As such a photosensitive polyimide, for example, a photosensitive polyimide precursor (a polyamic acid ester) in which a photosensitive group is introduced into the polyimide precursor by an ester bond is proposed in Japanese Patent Publication No. 30207/1980. This material which requires the use of an acid chloride group in synthesis of the photosensitive polyimide precursor has a disadvantage that a finally obtained photosensitive resin composition is easily contaminated with the chloride. Also, thermal cure of the polyamic acid ester to obtain the objective polyimide requires a high temperature, and therefore, the polyamic acid ester cannot be used when an element which cannot be heated at a high temperature is used.
As another example, a photosensitive resin composition which mainly comprises a mixture of a polyamic acid, an amine having a photoactive functional group and an azide compound as a photosensitizer is proposed in Japanese Provisional Patent Publication No. 168942/1982.
However, the photosensitive resin composition has a disadvantage that a thick film thereof cannot be formed.
Japanese Provisional Patent Publication No. 95697/1979 proposes a photosensitive resin composition which mainly comprises a mixture of a polyamic acid and a polymerizable unsaturated compound having a photoactive functional group. This photosensitive resin composition, however, has a disadvantage that it has a lower resolution as compared with a photosensitive resin composition which uses a photosensitive group-containing polyamic acid in which the photosensitive group is directly bound with the polyamic acid.